The present invention relates to manually powered wheeled vehicles, and more particularly to vehicles equipped to provide a higher level of upper body exercise as compared to conventional bicycles.
For many years, bicycles and other wheeled vehicles on the order of bicycles (e.g. tricycles) have provided recreation, exercise, and enjoyment as well as a useful means of transportation for individuals and their property. The exercise component is somewhat limited, however, in the sense that vigorous activity is concentrated along the lower body as the legs and feet move the pedals in circular paths to propel the drive sprocket. Another concern is the seated position of the rider, which can be a source of discomfort and fatigue over extended periods of use.
To address this latter concern and provide a vehicle propelled by elliptical motion, U.S. Pat. No. 6,648,353 (Cabal) discloses a vehicle on the order of a bicycle in which the rider stands upright while moving a pair of pedals in an elliptical path. To provide the elliptical motion while rotating a crank in a circular path, a pair of elongate foot supports are pivotally attached to the drive sprocket crank at one end while in each case the other end is free to move forwardly and rearwardly relative to a guide track. While this affords elliptical paths for the feet, the most vigorous exercise remains focused on the lower body. U.S. patent application Publication No. 2008/0116655 (Pate et al.) discloses a similar vehicle.
U.S. patent application Publication No. 2006/0009331 (Cheng) proposes a hand-driven vehicle propelled by the rider's arms. The rider stands on a rotatable platform linked to a turnable front wheel but not linked to the driving mechanism. U.S. Pat. No. 6,708,997 (Chait) proposes a hand-powered vehicle steered by leaning the vehicle. As with the Cheng vehicle, the rider stands on a platform that is not linked to the driving mechanism.
Stationary exercise devices have been developed in an effort to provide more balance between upper body and lower body exercise. For example, U.S. Pat. No. 7,175,568 (Eschenbach) shows an exercise apparatus in which the feet travel in elliptical paths while pivotally mounted levers exercise the arms. These exercise devices, often called elliptical cross trainers or simply elliptical trainers, have become very popular at health clubs in recent years.
A variety of mobile elliptical vehicles have been proposed. U.S. Pat. No. 5,775,708 (Heath) discloses a two-wheeled vehicle with push/pull cable steering in which the rider pivots hand levers, one at the top of each arm lever, to turn the front wheel. Riders may have difficulty maintaining the balance of the vehicle, given how the steering handles differ from a typical bicycle handlebar. For moving in a straight line, Heath's steering handles are oriented substantially horizontally and transversely. This positions the backs of the hands to face upward, which is ergonomically undesirable. Most stationary elliptical exercise machines are designed with the tops of arm levers substantially vertical, allowing the user to more comfortably reciprocate the arm levers.
U.S. Pat. No. 7,140,626 (Keay) describes a vehicle in which the rider stands on elongate foot supports or skis to drive two rear wheels. Vertical arm levers drive a single front wheel. Each of the skis is attached to crank arms at the front and at the rear, such that the rider's feet travel in a circular path. The steering method appears to be ergonomically difficult in that the rider must turn the front wheel by rotating a cross bar with the arm levers while reciprocating the arm levers fore and aft.
U.S. Pat. No. 7,223,210 (Krul et al.) describes a four-wheeled vehicle in which the rider stands on a pair of elongate foot supports or skis. The rear of each ski is rotatably attached to a drive crank at the rear of the vehicle. The front of each ski is pivotally attached to the bottom of a swing arm or lever near the front of the vehicle. During operation, the rear of each ski travels in a circular path, while the front of each ski traverses an arcuate path. The rider's feet trace an approximately elliptical or egg-shaped path. Krul allows the rider to use his or her hands to pivot upper sections of the arm levers either left or right to steer the front wheels. During steering, the vehicle and wheels remain substantially perpendicular to the riding surface.
U.S. Patent application Publication No. 2007/0001422 (Kraus) discloses a vehicle similar to Krul's, except with one wheel at the rear and two in front. The vehicle is rear-wheel driven and front wheel steered. In one embodiment, the frame and front wheels are allowed to tilt during a turn. To counteract the tendency of three-wheeled vehicles to tip over during turns, the tilting or leaning function allows the rider to move his or her center of gravity in the direction of the turn. While this may help to prevent tipping, the rider must be agile to control the initiation and extent of the lean, and return to an upright position.
In an alternative embodiment steering approach, Kraus uses pivotally mounted grip ends at the tops of the arm levers. The rider pivots the left grip end to turn left, and pivots the right grip end to turn right. The grip ends do not pivot in concert. Rather, it appears that simultaneous pivoting of the grip ends would apply counteracting forces in a simultaneous attempt to turn the wheel right and left.
In the Krul and Heath vehicles, the rider initiates front wheel toe steering by pivoting upper ends of the arm levers toward the direction of the turn. For example, to initiate a left turn, the rider would use his or her hands and forearms to pivot the tops of both arm levers toward the left. One problem with this method is that while the rider applies a leftward force vector to pivot the upper ends of the arm levers, the upper body tends to counteract the force by leaning to the right. This increases the tendency to tip. For better balance, the rider should lean into the direction of the turn, or at least avoid leaning in the direction opposite the direction of the turn.
Another problem with the Krul and Heath steering approach is that the pivotable upper ends of the arm levers are spaced apart from the planes in which the arm levers reciprocate. This spacing or misalignment varies as the upper ends are pivoted, and causes the hands and arms, when reciprocating the arm levers to propel the vehicle, to also apply an undesirable torque or rotational force to the arm levers. The result is an unwanted twisting along the arm levers, reducing efficiency and generating stress concentrations that can lead to metal fatigue and plastic deformation or fracture.
During operation of the Krul and Kraus vehicles, the rear ends of the skis trace circular paths due to the crank, and the front ends of the skis trace arcuate paths due to the arm levers. This arrangement results in the rider's feet being in a heel-higher-than-toe orientation during much of each cycle of the ski. Crank rotation entails considerable vertical travel of the rear end of each ski, in combination with a less pronounced vertical travel of the ski forward end. Further, the front end oscillates vertically at twice the frequency of the rear end. This causes a rocking action in the skis, and essentially requires locating the crank near the rear end of the vehicle with the thrust levers in front. Some riders prefer a motion that is closer to stair climbing, and also prefer reduced rocking action for smoother operation.
While the vehicles taught by Kraus, Krul, Heath and Keay may usefully combine upper body and lower body exercise, none of them accommodates the tendency of the shoulders and arms to become fatigued earlier than the legs and feet during extended operation of the vehicle.
Therefore, the present invention has several aspects directed to one or more of the following objects:                (i) to provide, in a vehicle driven at least partially by hand operated thrust levers, ergonomic thrust lever hand controls that efficiently utilize push/pull forces of the arms and shoulders without applying undesirable rotational moments or torsion to the thrust levers;        (ii) to provide, in a vehicle powered simultaneously through hand operated thrust levers and leg powered drivers, an indirect coupling of the drivers to a drive crank for smoother operation and reduced rocking action;        (iii) to provide a steering system for a vehicle powered by hand operated levers, comprised of separate subsystems, one operable from the thrust levers and the other operable independently of the thrust levers; and        (iv) to provide, in a vehicle powered at least partially by hand operated thrust levers, more natural and user-friendly thrust lever steering controls.        